<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
</head>
<body>

</body>
</html>


<script>
	var arr = new Array(30);
	for(var i=1;i<=30;i++){
		arr[i]=2*i
	}

	alert(arr)
</script>